A visible light communication (VLC) technology is a technology in which communication is performed by using a visible light spectrum (380 nm to 780 nm). In the VLC communications technology, a signal is modulated at a transmit end, to obtain an optical signal of a light source (such as a light emitting diode (LED)), and the optical signal is received at a receive end by using an optical-to-electrical receiving unit, to complete high-speed signal transmission.
In VLC communication, one VLC network may include a plurality of visible light communication personal area networks (VPAN), and each VPAN is configured to serve user equipment (Device) in the VPAN. A coordinator is disposed in each VPAN. The coordinator is usually used to perform management and service transmission for the VPAN, and the coordinator may be disposed on a light source in VLC. Because a light source usually has a relatively small lighting range, in the VLC network, a VPAN also has a relatively small size, for example, a range of several square meters. A plurality of VPANs usually exist within a specific range. Coordinators in adjacent VPANs are connected by using a backhaul link, and the backhaul link may be used to implement communication between the VPANs.
When a device needs to transmit a service, the device searches for a surrounding VPAN, and is connected to a suitable VPAN for service transmission. When a VPAN is overloaded and the like, the VPAN requests a device in the VPAN to leave the VPAN. After leaving the VPAN, the device performs VPAN search again, and then selects a suitable VPAN from a found VPAN for access.
A process in which the device performs VPAN search mainly includes: receiving a beacon frame sent by a coordinator in a VPAN. Each VPAN periodically transmits the beacon frame, to ensure that the VPAN can be found by the device. However, because a plurality of VPANs usually exist within a specific range, interference between the VPANs may be relatively strong.
To resolve a problem of interference between beacon frames, the following solutions are usually used in the prior art: First, all VPANs send beacon frames by using different beacon slots; second, all VPANs send beacon frames by using different logical channels; and third, all VPANs send beacon frames by using different modulation frequencies.
Although the foregoing three solutions all can be used to resolve the problem of interference between beacon frames, because the device needs to receive the beacon frame on a plurality of beacon slots, a plurality of logical channels, or a plurality of modulation frequencies in the foregoing three solutions, the device needs to consume extremely long time to perform search. This causes extremely long access time, and consequently user experience is affected.